1. Field of the Invention
The present invention relates generally to portable fire extinguishers and, more particularly, to an improvement in a handle for a portable fire extinguisher which activates a valve controllably releasing the pressurized contents.
Portable fire extinguishers are well known in the art. Controlled release of a pressurized fluid, in fire extinguishers or any other use, is likewise well known in the art. However, improvements in controlled release of fire extinguisher fluids have continuously been tried and proposed. The search is never ending, as in any art, for a more efficient, more dependable and less expensive control means.
The instant invention represents a novel approach to solving the problems of controlled release while seeking to solve all three of the above goals. In this respect, the number of parts involved is reduced thus cutting the expense and simplifying assembly and servicing. At the same time, the simplification of servicing in particular benefits the efficiency and dependability of the device.
2. Prior Art
Although portable fire extinguishers have been around for a long time, the present invention deals more specifically with a controllable release mechanism for a fluid under pressure in a fire extinguisher. As such, the prior art of concern is that dealing with mechanisms for controlled release.
One of the earliest such mechanisms for controlled release is taught by U.S. Pat. No. 2,067,829 wherein a plunger F serves as both a punch for opening a diaphragm and a sealing valve. In this case, the activation of the extinguisher is controlled by lifting the trigger H once the sealing diaphragm has been broken. When the trigger is lifted the seal F.sup.2 of the plunger F is spaced from the valve seat E' to allow the fluid to escape. Since the plunger is spring biased, releasing the trigger reseats the valve and stops the escaping fluid.
A considerable improvement with respect to controlled release in fire extinguishers is shown by U.S. Pat. No. 2,506,074. This patent utilizes, by now, practically conventional portable fire extinguisher components, e.g., tank 7, valve body 10, plunger 29 and pick-up tube 17. To the top of the valve body a cap 37 and pair of handles 45 and 52 are attached. The handle 45 pivots about pin 48 on the cap and the handle 52 pivots about pin 53 on the handle 45. The addition of the sliding plunger 54, controllably releases the pressurized fluid when the handles 45 and 52 are properly orientated.
The claimed advantage in U.S. Pat. No. 2,506,074 is that the fluid is released when the handle 52 is pressed into the handle 45 while the handle 45 is being lifted towards point 43 of the cap. However, if the handle 45 is not lifted, fluid will not be released regardless of the pressing of handle 52.
Admittedly, the mechanism of U.S. Pat. No. 2,506,074 is unique in providing operative and inoperative handle or trigger positions. Unfortunately, most persons under conditions requiring the use of a fire extinguisher may not be able to appreciate the intricate design of the mechanism. In fact, the inoperative feature may cause serious problems when a potential user neglects to lift handle 45 prior to attempting to utilize the extinguisher. While this criticism is not meant to downgrade the uniqueness of the mechanism of the patent, the drawback with regard to the efficiency of the unit must be considered.
Another mechanism for controllably releasing a fluid under pressure from a fire extinguisher is shown by U.S. Pat. No. 2,530,092. In this case, there is only one handle connected to the tank by a pivot and a valve plunger by a pivoted link. Operation is affected by lifting the handle which in turn lifts the valve plunger off a seat and releases the fluid. The pivoted link provides two stable positions, blocking release and allowing release of the fluid, respectively.
Finally, U.S. Pat. No. 3,359,149, while claiming a locking feature for the valve handle mechanism, shows a valve handle mechanism very similar to that which is most often utilized on pressurized, portable fire extinguishers.
Two handles, operated by gripping and pulling the two together, relatively, is the means used to operate the valve plunger in U.S. Pat. No. 3,356,149 and most recent portable fire extinguishers. Each of the two handles are pivotally attached at separate pivot points to the valve body or some extension thereof. Clearly, the valve body, or an extension thereof, is required to be specially machined, cast or otherwise formed, in order to accommodate the pivoting of both handles. The pivoting of both handles separately increases the cost of manufacturing and assembly of the unit. But further, maintenance or servicing of the unit is rendered more complex and expensive as a result of the double pivot and extra parts.
U.S. Pat. No. 3,356,149, as noted above, claims an advantage in rendering the handles 14 and 21 self locking to prevent accidental discharge of the extinguisher. As mentioned above, the state of the user under the specific conditions applicable to the use of fire extinguishers may in fact result in the self-locking feature being a handicap rather than an advantage. This view of the claimed advantage is not meant to deny any uniqueness attributable to the patent by the inventor.